This invention concerns cards with a plastic body and a snap-off module held to the said card body by three ties, this snap-off module including, firstly, a substantially rectangular thin plastic body of which one edge in the corner is cut so as to form a means of foolproofing and, secondly, a microcontroller electrically connected to contact pads flush with the surface of the said module.
Such cards, often called SIM (Subscriber Identification Module) cards, are mainly intended for the field of mobile telephony where telecommunication network operators demand that the access to the services they propose is only possible through the use of a secured system. In practice, when a member of the public wants to access a telecommunication network, he first purchases a SIM card. This person is then known as a subscriber to the network and has for example access rights which are partly managed by the card.
Once the person has purchased a SIM card, he connects this card to his mobile telephone. Some mobile telephones only accept cards in ISO format, i.e. whose dimensions, approximately 85.6 mm long, 54 mm wide and 0.76 mm thick, are provided for in the standard ISO7816. Other mobile telephones however only accept SIM cards in mini-card format, i.e. whose dimensions, approximately 25 mm long, 15 mm wide and 0.76 mm thick, are provided for in the standard ETSI/GSM11.11. Consequently, depending on the model of mobile telephone that the subscriber has, he may need to detach the snap-off module from the card body in order to insert it in his telephone.
In the prior art shown on FIGS. 1 and 2, module 3 is built into the card body 2 such that the contact pads 5 flush with the surface of the said module 3 are located at the positions defined in the above-mentioned standard ISO7816. The means intended to hold the module 3 to the card body 2 consist of four ties. A large tie 13 connects the width edge opposite the edge in the corner 6 cut so as to form a means of foolproofing, i.e. on the above-mentioned figures the left edge of module 3, to the card body 2 and three ties of reduced width 20, 21 and 22 connect respectively the top edge, the bottom edge and the right edge of the module 3, to the said card body 2. The longitudinal cross-section of these last three ties is highly trapezoidal.
To detach module 3 from a card, the person must exert pressure on the module in order to break the ties of reduced size 20, 21, 22 then bend one or more times the large tie 13 to finally break it. Separation of module 3 is irreversible.
The cards with snap-off module described above in the state of the art technology do not have sufficient mechanical resistance to the dynamic flexions and torsions for them to comply with standards ISO7816-1/ISO10373 which require that cards in ISO format must withstand 500 flexions in the direction of the length with a deflection of 20 mm (FIG. 3A) then 500 flexions in the direction of the width with a deflection of 10 mm (FIG. 3B). In fact, when such cards are subject to 500 dynamic flexions in the direction of the length, tie 22 undergoes a maximum elongation of approximately 100% and, when these cards are subject to 500 dynamic flexions in the direction of the width, tie 21 undergoes a maximum elongation of approximately 181%. A maximum elongation of 100% for a given tie means that part of this tie suffers a theoretical maximum elongation consistent with its length being doubled. In practice, the tie snaps before reaching the 500 flexions.
Moreover, in spite of the fact that they offer insufficient resistance to the flexions and torsions, the snap-off modules of the cards using the state of the art technology are no easier to detach from the card body considering the presence of four ties.
We may also mention the patent application EP 0 521 778 A1 which concerns the manufacture of smartcards. To reduce the cost of manufacturing smartcards in smaller format than usual, all manufacturing steps including the testing and the printed personalisation of the visible surfaces of the card are carried out on a card of standard format. At the end of the process a card of reduced format is blanked from the standard card. A partial pre-cut is made along a line, either by thinning the card all around the perimeter of the reduced format card, or by a slit following this perimeter, this slit being interrupted locally to leave temporary supporting bridges between the reduced format card and the remainder of the standard card.
Patent DE 0 535 436 A2 concerns a smartcard including a detachable module. This module is connected to the card body by ties and at least one attachment element. When the ties are broken, the module keeps the same position in its housing due to the attachment element.
Patent DE 197 26 203 C1 concerns a smartcard including a card body in which there is a substantially rectangular and irreversibly detachable module. The limit between the card body and the module is cut around virtually all the perimeter. The part of the contour which is not cut is a line which is scored slightly. Opposite this scored linear area there is a triangular notch.
Also, a problem which the invention proposes to solve concerns the realisation of cards with a plastic card body and a snap off module held to the said card body by a first and a second lateral tie, this snap-off module including, firstly, a substantially rectangular thin plastic body the having a beveled edge so as to form a means of foolproofing and, secondly, a microcontroller electrically connected to contact pads flush with the surface of the said module, the said cards offering greater resistance to stresses under flexion and under torsion than the similar cards in the state of the art technology.
The proposed solution of the invention to the above-mention problem concerns a card characterised in that the snap-on module is in addition held to said card by an angular tie, the said angular tie connecting the bevelled edge of the module to the card body.